How to use an if statement inside the draw function to change the UI at runtime?
Found the problem, 'icons' wasn't recognized because it was from a different class, I just had to reference it.

icons = scene.ignit_panel.icons

if icons == 'Brightness':
    row.prop(scene.ignit_panel, "brightness_icon")
elif icons == 'Backlit Keys':
    row.prop(scene.ignit_panel, "backlit_keys_icon")
elif icons == 'Volume':
    row.prop(scene.ignit_panel, "volume_icon")